Title: Influence of landscape heterogeneity on water available to tropical forests in an Amazonian catchment and implications for modeling drought response: Water Available to Tropical Forest

Abstract

The Amazon basin experienced periodic droughts in the past, and climate models projected more intense and frequent droughts in the future. How tropical forests respond to drought may depend on water availability, which is modulated by landscape heterogeneity. Using the one-dimensional ACME Land Model (ALM) and the three-dimensional ParFlow variably saturated flow model, a series of numerical experiments were performed for the Asu catchment in central Amazon to elucidate processes that influence water available for plant use and provide insights for improving Earth system models. Results from ParFlow show that topography has a dominant influence on groundwater table and runoff through lateral flow. Without any representations of lateral processes, ALM simulates very different seasonal variations in groundwater table and runoff compared to ParFlow even if it is able to reproduce the long-term spatial average groundwater table of ParFlow through simple parameter calibration. In the ParFlow simulations, the groundwater table is evidently deeper and the soil saturation is lower in the plateau compared to the valley. However, even in the plateau during the dry season in the drought year of 2005, plant transpiration is not water stressed in the ParFlow simulations as the soil saturation is still sufficient to maintain amore » soil matric potential for the stomata to be fully open. This finding is insensitive to uncertainty in atmospheric forcing and soil parameters, but the empirical wilting formulation used in the models is an important factor that should be addressed using observations and modeling of coupled plant hydraulics-soil hydrology processes in future studies.« less

Authors:

Fang, Yilin  ^[1];

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Leung, L. Ruby  ^[2];

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Duan, Zhuoran ^[1]; Wigmosta, Mark S. ^[1]; Maxwell, Reed M. ^[3]; Chambers, Jeffrey Q. ^[4]; Tomasella, Javier  ^[5]

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• Search OSTI.GOV for ORCID "0000-0003-2597-8833"
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+ Show Author Affiliations

1. Earth Systems Science Division, Pacific Northwest National Laboratory, Richland Washington USA
2. Atmospheric Science and Global Change Division, Pacific, Northwest National Laboratory, Richland Washington USA
3. Department of Geology and Geological Engineering, Colorado School of Mines, Golden Colorado USA
4. Earth Sciences Division, Climate Sciences Department, Lawrence Berkeley National Laboratory, Berkeley California USA
5. Centro Nacional de Monitoramento e Alerta de Desastres Naturais, São Paulo Brazil

Publication Date:

Fri Aug 18 00:00:00 EDT 2017

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1398175

Report Number(s):

PNNL-SA-125270
Journal ID: ISSN 2169-897X; 830403000

DOE Contract Number:  

AC05-76RL01830

Resource Type:

Journal Article

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 122; Journal Issue: 16; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English